Diagnostic methods based on an antigen-antibody reaction in a gel are well-known in the art. In recent years the methods employing radial immunodiffusion like that described by Mancini et al. (Protides Biol. Fluids 11, 370, 1964) and methods utilizing the electroimmunoassay of Laurell (Anal. Biochem. 15, 45, 1966) have become so widespread that ready to use plates and standards are commercially available for measuring human serum proteins, particularly the immunoglobulins A, G and M. Unfortunately these methods have the disadvantage of giving large errors in quantitation which have been demonstrated when the tested samples and standards diverge in character, for example, in regard to molecular size.
With the Mancini's method differences in diffusibility are held culpable while for Laurell's method, among other things variations in electromobility and diffusibility are considered responsible for quantitating discrepancies.
Additional prior art in this area includes U.S. Pat. No. 3,853,468 which utilizes a substrate coated with a substance, i.e., acrylic or other plastic, which has affinity for nonagglutinated particles as a means of determining the presence or absence of antibodies or antigens in sample biological fluids. The patent also describes use of an absorbent material to remove non-absorbed material. Furthermore, U.S. Pat. No. 3,905,767 detects the antibody-antigen reaction by incorporating one component as part of a gel and adding the other component to the surface to form a precipitate on the surface. Light scattering is utilized to detect the presence of the precipitate.